Demolition hammers are used on work sites to break up hard objects such as rocks, concrete, asphalt, frozen ground, or other materials. The hammers may be mounted to machines, such as back hoes and excavators, or may be hand-held. Such hammers may include a pneumatically or hydraulically actuated power cell having an impact system operatively coupled to a tool that extends from the hammer to engage the hard object. The impact system generates repeated, longitudinally directed forces against a proximal end of the tool. The distal end of the tool, extending outside of the housing, may be positioned against the hard object to break it up.
During operation, the hard objects may need to be rearranged or reoriented to better position them for breaking by the hammer. Hammer manufacturers discourage operators from using the tool to rearrange or reorient the hard objects because excessive side forces on the tool may damage the tool, seals, bushings, or other hammer components. As a result, hammer manufacturers may include rock claws on the hammer that are used to push against the hard objects while protecting the hammer housing and tool.
Rock claws are areas on the bottom portion of a hammer that are built-up to absorb the abrasion and wear from frequent pushing and scraping against hard objects. Most manufacturers provide a rock claw by extending an end plate of the hammer out beyond the profile of the housing. The cantilevered portion of the end plate is typically reinforced with other plates and gussets for strength.
After extended use, the end plate must be replaced due to wear on the rock claw portion. Since, however, the end plate is structurally a part of the functioning hammer (i.e. the end plate helps support other portions of hammer housing and power cell), replacing the end plate requires additional care, such as, for example, holding the housing structure square while the end plate is replaced.